#include<bits/stdc++.h>
using namespace std;
int m,n,sx,sy,zx,zy,ans=INT_MAX;
char a[50][50];
int fx[4]={0,1,0,-1}; 
int fy[4]={1,0,-1,0};
void dfs(int x,int y,int step){
    if(step>ans) return;
    if(x==zx&&y==zy){
        ans=min(ans,step);
    }
     
    for(int i=0;i<=3;i++){
        int tx=x+fx[i];
        int ty=y+fy[i];
        if(tx>=1&&tx<=m&&ty>=1&&ty<=n&&a[tx][ty]!='#'){
            a[tx][ty]='#';
            dfs(tx,ty,step+1);
            a[tx][ty]='.';
        }
         
    }
     
}
int main(){
    cin>>m>>n;
    for(int i=1;i<=m;i++){
        for(int j=1;j<=n;j++){
            cin>>a[i][j];
            if(a[i][j]=='@') sx=i,sy=j;
            if(a[i][j]=='*') zx=i,zy=j;
        }
    }
    a[sx][sy]='#';
    dfs(sx,sy,0);
    if(ans==INT_MAX) cout<<-1;
    else cout<<ans;
 
    return 0;
}
/**************************************************************
	Problem: 1900
	User: zhangzekai
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2076 kb
****************************************************************/